In recent years, the need for high-speed transmission of signals within a system device or between devices has been rapidly increasing, and the development of optical interconnection has become active. Optical interconnection is a general term for technology for converting electrical signals to optical signals and transmitting light including communication information over an optical fiber or the like.
In optical interconnection such as that described above, a connector in which a plurality of optical fibers are arranged in an array is connected to an optical module, and multi-channel optical communication is actualized.
In optical modules for multi-channel optical communication, a type of optical module is known in which, to achieve compactness, a plurality of photoelectric conversion elements (light-emitting elements and light-receiving elements) are arranged on a substrate in an array such as to have an optical axis in a normal line direction of the substrate surface, and a connector in which the same number of optical fibers as the number of photoelectric conversion elements are arranged in an array such as to have an optical axis in a direction perpendicular to the optical axis of the photoelectric conversion elements is attached to a lens array.
Furthermore, in recent years, to actualize faster signal transmission, a lens array to which a connector in which a plurality of optical fibers are arranged in an array of two rows is attached and actualizes multi-channel optical communication, and an optical module including the lens array have been developed (for example, FIG. 13A and FIG. 13B in Patent Literature 1).
In a lens array (optical member 22) in Patent Literature 1 (FIG. 13A and FIG. 13B), light emitted from each light-emitting element (VCSEL 30) enters from a first lens (collimate lens 70), and light is emitted from a second lens (condensing lens 75) towards an end surface of each optical fiber (10). In addition, in the lens array (optical member 22) in Patent Literature 1 (FIG. 13A and FIG. 13B), light emitted from each optical fiber (10) enters from a third lens (collimate lens 76) and light from a fourth lens (condensing lens 77) is emitted towards each light-receiving element (PD 32).    Patent Literature 1: Japanese Patent Laid-open Publication No. 2006-344915